well seeing as it sounds like a 1.3 ohv engine, the headgasket swap is pretty much a piece of piss, as its a push rod lump, and essentially the cam is part of the bottom end, so very few things to disconnect and unbolt

but if ur diagnosing the headgasket due to losing all your oil, id say ur a tad off the mark, maybe i smacked ur sump and damaged that, or the sump gasket.

most basic thing to do is get it up on axle stands and stick ur head under, see whats leaking and where from, and then get back to us

oh and headgasket, infact full gasket sets dnt cost much at all for these, all my local motorfactors have always got me bits for mine wen it was stil 1.3 engined